Not applicable.
This invention relates to three-wheeled vehicles, specifically, to an improved steering mechanism that leans wheels and body into turn.
Many types of arrangements have been proposed for leaning body and wheels into a turn in order to increase a vehicle""s stability by counteracting the cornering forces that tend to make vehicles unstable during turns and tip over or throw operator out. Soohoo, U.S. Pat. No. 5,762,351, Klopfenstein, U.S. Pat. No. 4,903,857, and Cocksedge, U.S. Pat. No. 4,634,137, all show pedal-powered lean-steer tricycles with high centers of gravity with operator aboard and upright riding position which is uncomfortable and produces high wind-resistance.
Fujita, U.S. Pat. No. 4,650,213, and Boume, U.S. Pat. No. 4,624,469, show motor-driven lean-steer tricycles, both are heavy and so, unsuited for pedal power.
Patin, U.S. Pat. No. 4,921,263, Miksitz, U.S. Pat. No. 4,998,596, Mason, U.S. Pat. No. 5,568,935 and Stites, U.S. Pat. No. 6,062,581 all show leanable tricycles with a single front wheel and two rear wheels, which is fine for straight line motion but, when executing a turn at high speed and braking, the forward momentum of the operator, combined with centrifugal forces, overpowers the stability of the single front wheel and either tips the vehicle over or ejects the operator. Conversely, in a vehicle with two front wheels spaced apart, the centrifugal forces and forward momentum of the operator are sustained by the forward outside wheel, giving much more support where the forces are directed.
Accordingly, there exists a need for a vehicle that combines the qualities of: being light, so that it is easy to pedal or be powered by a small, energy-efficient motor; recumbently seated for comfort, enhanced pedaling, reduced wind resistance and lower center of gravity; at least two wheels spaced apart near front of vehicle for support during turns and braking; capable of wheel and body lean to reduce side-loading forces on wheels and improve cornering capabilities.
A recumbent-seated, 3 wheeled, pedal powered vehicle comprising two frames pivotally connected perpendicular to each other with steering mechanism that allows for leaning body and wheels into a turn and independent adjustment of the turning radius, while inducing an effect to the 2 front wheels similar to Ackerman steering compensation, where the inside wheel turns more sharply than the outside wheel, reducing scrubbing of tires during turns.
Steering is accomplished by leaning body right or left and rotating steering levers by use of arms and hands to maneuver through turns. From straight line motion, lean must be initiated through use of arms and hands to enter a cornering mode. Balance during turns is accomplished by adjusting amount of body lean to compensate for centrifugal force and rotating steering levers for sharpness of turn. Seat is positioned to optimize the operator""s center of gravity so the amount of effort needed to keep the body in a balanced position is not excessive; thus, providing a vehicle with wheel and body lean, that has excellent handling characteristics and is virtually tip-over proof and rightable from maximum lean at standstill.
Several objects and advantages of my invention are: recumbent seat for comfort, enhanced pedaling, reduced wind resistance, and lower center of gravity than standard bicycle seat and upright pedaling. The recumbent position is roughly defined as where the operator is reclining in a feet-forward position. This keeps the operators legs relatively horizontal during pedaling. Since the thighs of the operator do not move down below the level of the seat, the seat can be of full width. Additionally, this position provides an ergonomic seat backxe2x80x94the seat can support the buttocks and spine of the operator for increased comfort and efficiency.
Another object of the invention is to provide a steering mechanism that leans wheels and body into a turn to compensate for centrifugal forces, also providing the advantage of moving the center of gravity closer and lower toward the center of the turn and, at the same time, moving the contact patch of the tires farther out from the center of the turn. This leaning effect is advantageous in human powered vehicles because it conserves energy by avoiding braking during turns.
Another advantage is the reduction or elimination of side loading forces in a turn; this allows for the use of lighter weight wheels and tires, since essentially only radial forces are applied to the wheels during a turn. The lighter wheels and tires further enhance the handling characteristics of the tricycle by reducing the gyroscopic forces that must be overcome to steer.
The steering mechanism also has the advantage of providing a similar effect to xe2x80x9cAckerman Steering Compensationxe2x80x9d, where the inside wheel turns more sharply than the outside wheel, thus reducing the scrubbing of tires. This design achieves better handling characteristics through a simpler design than other wheel and body lean vehicles, thus improving upon prior art.
Another advantage is that reduced side-loading stress permits use of lighter construction materials. A variety of rigid, lightweight materials could be used to manufacture the tricycle, including, but not limited to, steel, aluminum, titanium, carbon fiber. All of the bicycle components, i.e. pedals, crank, chain, gears, derailers, shifters, brakes and brake levers, (if motor-driven, throttle and clutch as on motorcycles) are readily available or easily made by one knowledgeable in the art; no special manufacturing processes or requirements needed.
With a lightweight frame, shock-absorbing suspension is not necessary, since the majority of mass is the operator. Mounting the seat on springs or providing a seat cushion or attaching a sling seat to the seat frame with shock cords would improve comfort without adding significantly to vehicle weight.
Hands and arms are used on steering levers to control both leaning and steering of tricycle, so it is easily and quickly adjusted for changing road conditions and obstacles.
Another object of the invention is the turning radius is independently adjustable in relation to the amount of wheel and body lean induced by the operator, allowing the operator to make wide or tight turns at variable speeds or g o straight and lean body to compensate for road conditions such as pitch or crown or uneven pavement. This quality produces a tricycle with excellent handling and stability at all speed and road conditions. Other advantages of tricycle of invention:
1. Due to increased stability, track width may be reduced.
2. Greater stability than bicycles when riding in windy conditions.
3. Easy starting and stoppingxe2x80x94no need to take feet off pedals to balance when stopped.
4. Superior braking and load bearing capacity to bicycle.
5. Provides a stable platform that may be fully enclosed and streamlined for speed and comfort.
6. Further, a human or engine-powered version would provide a viable commuter or sport vehicle, suitable for races, recreation or exercise.
One disadvantage is that, if leaned to either maximum point while at a standstill, greater effort is needed to return the body to vertical apex; however, at all but the lowest speeds, the gyroscopic effect of the wheels helps balance the body upright. Additionally, positioning of seat height and inclination affects the operator""s center of gravity and so can reduce the amount of effort needed to return the body to a vertical balanced position.